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Overview 0 November 18, Large flashover fire on an escalator 0 Killed 31 people 0 Injured more than sixty 0 Result of many safety hazards 0 Aftermath of fire included implementation of numerous safety regulations

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Root Causes 0 Several combustion points found on escalators 0 All on right hand side 0 Several gaps in escalator treads found 0 Large build-up on track analyzed 0 Found to be easy to ignite 0 Fires extinguished themselves in 9 minutes 0 No evidence of flash fire

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Root Causes 0 Debated continued over the cause of the flash fire 0 Ceiling paint? 0 Piston effect? 0 Neither explanation was very good

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Root Causes 0 Computer modeling done by a research establishment (Harwell) 0 Simplifications made 0 Several configurations considered 0 Unexpected occurred: 0 Hot gas remained in the trench of the escalator 0 Flames burned parallel to 30º angle of the track 0 Thought to be impossible 0 Model was suspected to be faulty

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Root Causes 0 Scale replica of the escalator was built and lit 0 Flames performed as in simulation 0 Situated themselves parallel to the escalator 0 Heated wooden treads to ºC 0 Led to treads flashing 0 New phenomena now known as the “trench effect”

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Ultimate Results 0 Why was this the first time a small fire flashed over? 0 Complete lack of attempt to put out the fire 0 Exact position of fire across width of escalator 0 Found to be conducive to trench effect

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Ultimate Results 0 Damage from fire fixed quickly 0 Ticket hall and platforms for most lines opened next day 0 Ticket halls for most affected lines opened in stages over next four weeks 0 Nobody was prosecuted for this disaster 0 No justification for charges